Hercules beetles are some of the largest beetles and indeed, some of the largest insects alive today. The larva of Scarabaeidae. Beneath the cephalic horn reside large eyes and distinct lamellate antennae (a straight stalk with right angled fingers at the terminus). The elytra (hardened front wings which create a shell around the abdomen) of are noteworthy in that they change color with varying humidity levels. In low humidity, the elytra appear yellow to olive green but they turn stark black with rising moisture levels. The mechanism responsible for this change is the intricate microstructure of the elytra that modifies light refraction as it is exposed to moisture. (Beebe, 1944; Campbell, 2012; Hinton and Jarman, 1973; Kasahara, 2006)in its later instars (larval growth stages) can weigh up to 140 grams and barely fits in the outstretched hand of a male adult human. Upon pupating and emerging as adults the beetles actually lose some of their larval mass but still retain an imposing size. The most obvious and striking features of the adult male are the long horns that arise from the thorax (thoracic) and head (cephalic). Together, these appendages mimic both the appearance and function of a large claw. When measured from the end of the longer, thoracic horn to the tip of the abdomen, adult males average around 78 mm in length, though there are reports of massive males on the island of Guadeloupe reaching 180 mm long. Females lack horns and are smaller, averaging 61.8 mm long. The rest of the beetle’s physical characteristics are typical, albeit larger, for the family
Like all beetles, (Kasahara, 2006)goes through complete metamorphosis with egg, larval, pupal, and adult stages. Once the egg is laid, it develops for 1 month before hatching into a larva. The larval stage can last from 12 to 18 months before the 2 to 3 month pupal stage. Sexual maturity occurs upon emergence of the adult, or imago beetle.
There has been little research into the reproductive cycle of Hercules beetles. The few studies that have observed mating (Beebe, 1944)have noted no seasonality with respect to the willingness to mate.
Hercules beetles have never been observed to provide any type of parental care beyond egg laying. It is likely, as with other beetles, the eggs are laid directly into the decaying wood of a fallen tree where the larvae will live upon hatching, and then abandoned. Females likely do provide provisioning in the eggs though. (Kasahara, 2006)
All information on Hercules beetle lifespan has been collected under artificial conditions. These data nonetheless give a general idea of the longevity of the species. The egg incubates for around one month before hatching into a larva. The larval stage can last from 12 to 18 months before the 2 to 3 month pupal stage. Once emerged, the adult beetle can live for 8 to 12 months making the potential lifespan 34 months. (Kasahara, 2006)
Like most insects, communication within the species is a mix of chemoreception (the sensing of chemicals with specialized pores or appendages), sight, and mechanical perception. (Beebe, 1944; Jarman and Hinton, 1974)is also likely able to detect vibrations. Experiments have shown that a male placed in the vicinity of a female will immediately orient towards her and seek her out. This is evidence of communication through strong sexual pheromones. The huffing or hissing sounds produced when disturbed serve to communicate a warning to potential predators.
Hercules beetles are herbivorous with the larvae feeding on rotting wood and the adults foraging for fallen, rotting fruits among the undergrowth. In controlled settings they have been observed devouring bananas and mangos. They first pierce the skin of the fruit with their mouth parts then proceed to masticate the surrounding tissue into a soft, easy to process pulp. Given the opportunity, (Beebe, 1944; Rassart, et al., 2008)will feed uninterrupted for up to 24 hours in artificial conditions.
No predation events onhave been observed and documented. Predators, especially on the succulent larvae, may include birds, bats, and small mammals such as rats.
Though no official studies of the ecological role of (Rassart, et al., 2008)have been conducted, based on the diet of decaying matter in both larval and adult forms, Hercules beetles aid in biodegradation and cycling of nutrients.
Hercules beetles are in high demand within the beetle enthusiast trade, which is especially prevalent in Japan. Large specimens of certain subspecies of (Kasahara, 2006; "Insect Price List/Dynastidae", 2013)can sell for as much a $700 dollars.
There are no known adverse effects ofon humans.
Andy Kulikowski (author), University of Wyoming, Hayley Lanier (editor), University of Wyoming - Casper, Angela Miner (editor), Animal Diversity Web Staff.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
helps break down and decompose dead plants and/or animals
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the business of buying and selling animals for people to keep in their homes as pets.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
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Blum, M. 1979. Sexual Selection and Reproductive Competition in Insects. Waltham, MA: Academic Press, Inc.
Campbell, C. 2012. "http://www.naturalworlds.org/scarabaeidae/species/Dynastes_hercules.htm." (On-line). naturalworlds.org. Accessed November 11, 2013 at
Dutrillaux, B., A. Dutrillaux. 2013. A South American origin of the genus Dynastes (Coleoptera: Scarabaeidae: Dynastinae) demonstrated by chromosomal analyses. Cytogenetic and Genome Research, 141/1: 37-42.
Hinton, H., G. Jarman. 1973. Physiological colour change in the elytra of the Hercules beetle, Journal of Insect Physiology, 19: 533-549..
Jarman, J., H. Hinton. 1974. Some defence mechanisms of Hercules beetle, Journal of Entomology Series A-Physiology & Behavior, 49/NOV7: 71-80..
Kasahara, . 2006. "The Breeding/Rearing of Dynastes hercules hercules" (On-line). Accessed November 07, 2013 at http://www.naturalworlds.org/scarabaeidae/manual/hercules/Dynastes_hercules_breeding_1.htm.
Rassart, M., J. Colomer, T. Tabarrant, J. Vigneron. 2008. Diffractive hygrochromic effect in the cuticle of the Hercules beetle New Journal of Physics, 10/3: 1-14..